As a technique to improve an output of an engine, known is a method which compresses intake air with a turbocharger and supplies an engine with the compressed intake air (supercharging). This method is widely used for automobile engines and the like. A turbocharger normally includes a rotary shaft, a turbine wheel disposed on an end side of the rotary shaft, and a compressor wheel disposed on the opposite end side of the rotary shaft. The rotary shaft rotates at a high speed in response to exhaust energy of exhaust gas being applied to the turbine wheel, and thereby the compressor wheel disposed on the opposite end side of the rotary shaft compresses intake air.
A force that moves the rotor shaft in the axial direction (thrust force) is applied to the rotor shaft of the turbocharger. Thus, the turbocharger includes a thrust bearing device for supporting the rotor shaft in the axial direction. As an example of such a thrust bearing device, Patent Document 1 discloses a thrust bearing device.
The thrust bearing device of Patent Document 1 is, as depicted in FIGS. 1 and 2 of the document, provided with a collar member (thrust bush 10) mounted to the outer periphery of the rotor shaft so as to be rotatable with the rotor shaft, and a thrust bearing (thrust disc 11) with an inner peripheral edge portion in engagement with an annular groove formed by the collar member. The thrust bearing has an outer peripheral edge portion fixed to the housing, and makes slide contact with the collar member that rotates with the rotor shaft at an inner peripheral edge portion, thereby receiving a thrust force that acts on the rotor shaft.
Lubricant oil is supplied to a sliding portion of the thrust bearing that makes slide contact with the collar member. Further, an oil deflector (deflector) 18 is disposed on an end surface of the thrust bearing, and an oil-drain space (the first chamber 20) is defined between the end surface of the thrust bearing and the oil deflector 18. The oil-drain space is formed so as to surround the periphery of the sliding portion of the thrust bearing. The oil deflector 18 has a function to collect lubricant oil that scatters from the sliding portion in accordance with rotation of the rotor shaft, and to discharge the collected lubricant oil to outside through an oil discharge port 24 formed below the oil-drain space.